A roof truss generally comprises two or more top chord members and one or more bottom chord members. The ends of the top chords are secured together, and the ends of the bottom chord(s) are connected to the lower, free ends of the top chords for forming the perimeter of the roof truss. One or more web members span between and interconnect the top and bottom chords. The web members are secured at their ends to the top chord(s) and to the bottom chord(s).
In building construction, the roof structure is formed from a plurality of trusses set out across a building frame on anywhere from about 12 to about 60 inch centers. When erected upon the building frame, the truss spans the wall frames of the building and is fixed to the top of wall support frames. The sub-roof material is then fastened to the top chords, and ceiling material may be fastened to the bottom chords. The reactions resulting from the combined roof live, dead, and wind loads, plus the dead loads of the roof trusses and the roof and ceiling assemblies, are transferred by the trusses to the top of wall support frames.
Historically, roof trusses have generally been constructed of wooden chords and web members. More recently, various types of metal trusses have become available. While the unit raw materials costs for metal trusses may be competitive with other building materials, metal trusses typically have not been competitive against wooden trusses. But using metal as the material of construction has a number of advantages, including relatively stable price, increased unit strength, design flexibility, durability, light weight, reliability, minimum waste in use, recyclability and noncombustability.
For the foregoing reasons, there is a need to provide a cost competitive light weight metal roof truss for use in applications for which wood trusses would be structurally sufficient. The new metal truss should be easy to assemble while providing the aforementioned benefits compared with trusses made from other building materials. The new metal roof truss should also require low capital investment to produce, be able to be adapted to mass production, and be able to be manufactured in a manufacturing facility or on a jobsite.